1. Field of the Invention
This invention relates to lead-free projectiles fired from rifles and pistols. More particularly, a copper jacketed bullet having an essentially pure tin core exhibits performance characteristics similar to lead without presenting the environmental hazards of lead. 2. Description of Related Art
Most bullets fired from pistols and rifles have a lead base alloy core, meaning the core is either entirely or more than 50%, by weight, lead. The environmental hazards of lead are well known. Lead containing bullets fired into the ground are suspected to cause ground water pollution through leaching. Another problem facing shooters is that when a bullet having exposed lead is fired, a lead-containing dust from the projectile is emitted. These lead fumes are toxic and, if inhaled, present a hazard to the shooter. An additional hazard, lead is leached into ground water from unrecovered bullets.
Many alternatives to a lead core bullet have been disclosed. U.S. Pat. No. 5,399,187 to Mravic et al. discloses a sintered bullet core formed from a combination of a material having a density less than lead and a second material having a density greater than lead. One disclosed combination is a mixture of tin and tungsten.
U.S. Pat. No. 5,500,183 to Noordegraaf et al. discloses a non-jacketed bullet formed from a tin base alloy that contains as an alloy addition one or more of copper, antimony, bismuth and zinc.
U.S. Pat. No. 5,679,920 to Hallis et al. discloses jacketed bullets having a core formed from twisted and swaged strands of zinc wire.
While the bullets disclosed in the above United States patents are lead-free, the cores of these bullets are harder than lead causing the bullets to have an unacceptable degree of ricochet. In addition, zinc containing cores may also pose an environmental hazard. Zinc fumes are noted in the ASM Handbook,Volume 2 as suspected to have a detrimental effect on health.
There remains, therefore, a need for a projectile that is both lead-free and zinc-free and has performance characteristics similar to that of a bullet with a lead base core. Among the performance characteristics of lead that enhance bullet performance are malleability, density and low cost.